Water Resources of Pakistan: Indus River System, Dams and Irrigation (O Level Geography)

Water resources is one of the most important topics in Pakistan Studies Paper 2. It links directly to agriculture, energy and population, so a strong understanding here helps across the whole paper.

The Indus River System

Pakistan depends mainly on the Indus River and its tributaries — the Jhelum, Chenab, Ravi, Sutlej and the Kabul River from the west. Most of the water comes from snowmelt and glacier melt in the northern mountains, plus monsoon rainfall in summer.

The Indus Waters Treaty (1960)

Signed between Pakistan and India with the help of the World Bank, the treaty gave the three eastern rivers (Ravi, Beas, Sutlej) to India and the three western rivers (Indus, Jhelum, Chenab) to Pakistan. To move water from the western rivers to areas once fed by the eastern rivers, Pakistan built link canals, barrages and dams.

Dams and Barrages

• Tarbela Dam on the Indus and Mangla Dam on the Jhelum — large storage dams used for irrigation and hydroelectric power.
• Barrages such as Guddu, Sukkur and Kotri on the Indus raise the water level so it can flow into canals.

Know the difference: a dam stores water in a reservoir; a barrage diverts water into canals and stores very little.

Methods of Irrigation

• Canal irrigation: the main method — perennial canals flow all year; inundation canals flow only when rivers are high.
• Tube wells: pump groundwater; useful where canal water is not enough, and help lower the water table.
• Karez: underground channels used in Balochistan, which reduce evaporation in a hot, dry climate.
• Wells and Persian wheels: traditional, small-scale methods.

Water Problems

• Waterlogging and salinity: seepage from unlined canals raises the water table; evaporation leaves salt on the surface and damages farmland.
• Siltation: reservoirs fill with silt, reducing their storage capacity over time.
• Water shortage: a growing population, wasteful flood irrigation and limited storage put pressure on supply.
• Floods: heavy monsoon rain can cause destructive flooding.

Solutions (Useful for Evaluation Questions)

• Lining canals to reduce seepage
• Building new dams and small reservoirs — with their costs and environmental effects
• Drip and sprinkler irrigation instead of flood irrigation
• Tube wells and drainage schemes to control waterlogging
• Awareness about saving water in homes and farms

When evaluating “Is building more dams the best solution?”, discuss advantages (storage, electricity, flood control) and disadvantages (cost, displacement of people, siltation), then compare with other solutions and give a clear judgement.

Frequently Asked Questions

What is the main source of water in Pakistan?

The Indus River system, fed mostly by snow and glacier melt from the northern mountains and by monsoon rain.

What causes waterlogging and salinity?

Seepage from canals and over-irrigation raise the water table; when the water evaporates, salts are left on the surface.